1. Field
This document relates to a liquid crystal display and a driving method thereof.
2. Related Art
As the information technology is developed, the market for display devices used as connection mediums between users and information is growing. Accordingly, the use of flat panel displays (FPDs) such as a liquid crystal display (LCD), an organic light emitting diode (OLED) display, and a plasma display panel (PDP) is increasing. Of these, liquid crystal displays are widely used because they have a high resolution and can be big as well as small.
The liquid crystal display comprises a liquid crystal panel comprising a transistor substrate, on which thin film transistors, storage capacitors, pixel electrodes, etc. are formed, a color filter substrate on which color filters, black matrixes, etc. are formed, and a liquid crystal layer positioned between the transistor substrate and the color filter substrate.
When a gate signal is supplied from a gate driver, the liquid crystal layer is driven by a voltage difference between a data voltage supplied from a data driver and a common voltage supplied from a power source, thus causing the liquid crystal display to adjust the amount of light incident from a backlight unit to display an image.
Recently, a light emitting diode (hereinafter, LED) is mainly used as a light source included in the backlight unit. A plurality of LEDs are connected in series in a string to form one unit light source. A plurality of LED strings may be connected in parallel.
Meanwhile, current deviation occurs in a LED string or between LED strings due to impedance difference. Also, a short occurs in an LED because of various causes. If a shorted-LED is detected, overcurrent flows through the corresponding LED string, and the LEDs and a device driving the LEDs are damaged.
Consequently, in the conventional art, an LED driver requiring three pins for each channel was used in order to detect a short and protect the device, and the three pins comprise a first pin for fine-regulating the current of an LED string, a second pin for monitoring the current of the LED string, and a third pin for regulating an output of a DC power source based on the monitored current, and detecting LED short/open.
However, such a structure as the conventional LED driver that requires three pins may have the problem of cost increase due to an increased number of pins in a device configuration. Thus, there arises a demand for a solution that reduces costs.